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Hormonal and Thirst Modulated Maintenance of Fluid Balance in Young Women with Different Levels of Habitual Fluid Consumption.
Johnson, EC, Muñoz, CX, Jimenez, L, Le Bellego, L, Kupchak, BR, Kraemer, WJ, Casa, DJ, Maresh, CM, Armstrong, LE
Nutrients. 2016;(5)
Abstract
BACKGROUND Surprisingly little is known about the physiological and perceptual differences of women who consume different volumes of water each day. The purposes of this investigation were to (a) analyze blood osmolality, arginine vasopressin (AVP), and aldosterone; (b) assess the responses of physiological, thirst, and hydration indices; and (c) compare the responses of individuals with high and low total water intake (TWI; HIGH and LOW, respectively) when consuming similar volumes of water each day and when their habitual total water intake was modified. METHODS In a single-blind controlled experiment, we measured the 24 h total water intake (TWI; water + beverages + food moisture) of 120 young women. Those who consumed the highest (HIGH, 3.2 ± 0.6 L·day(-1), mean ± SD) and the lowest (LOW, 1.6 ± 0.5 L·day(-1)) mean habitual TWI were identified and compared. Outcome variables were measured during two ad libitum baseline days, a four-day intervention of either decreased TWI (HIGH) or increased TWI (LOW), and one ad libitum recovery day. RESULTS During the four-day intervention, HIGH and LOW experienced differences in thirst (p = 0.002); also, a statistically significant change of AVP occurred (main effect of TWI and day, p < 0.001), with no effect (TWI or day) on aldosterone and serum osmolality. Urine osmolality and volume distinguished HIGH from LOW (p = 0.002) when they consumed similar 24 h TWI.
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Hydration status moderates the effects of drinking water on children's cognitive performance.
Perry, CS, Rapinett, G, Glaser, NS, Ghetti, S
Appetite. 2015;:520-7
Abstract
Changes in hydration status throughout the day may affect cognitive performance with implications for learning success in the classroom. Our study tested the hypothesis that the benefit of drinking water on working memory and attention depends upon children's hydration status and renal response to water intake. Fifty-two children aged 9-12 years old were tested under two experimental conditions. The treatment session (Water session) consisted of a standard breakfast with 200 ml water, a baseline test, consumption of 750 ml of water over a period of two hours and subsequently retested. No water was provided after breakfast during the control session. Changes in hydration were assessed via urine samples. Cognitive testing consisted of digit span, pair cancellation, and delayed match to sample tasks. Children who exhibited smaller decreases in urine osmolality following water intake performed significantly better on the water day compared to the control day on a digit-span task and pair-cancellation task. Children who exhibited larger decreases in urine osmolality following water intake performed better on the control day compared to the water day on the digit-span task and pair-cancellation task. These results suggest that focusing on adequate hydration over time may be key for cognitive enhancement.
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The effects of acute citalopram dosing on gastric motor function and nutrient tolerance in healthy volunteers.
Janssen, P, Van Oudenhove, L, Casteels, C, Vos, R, Verbeke, K, Tack, J
Alimentary pharmacology & therapeutics. 2011;(3):395-402
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Abstract
BACKGROUND It is unclear whether endogenous serotonin release is involved in the regulation of gastric motility and food intake. AIM: To study the effect of acute administration of the selective serotonin reuptake inhibitor citalopram on gastric motor function in man. METHODS Nineteen healthy volunteers underwent a gastric barostat, gastric emptying and/or a drinking test after dosing with either placebo or citalopram (20 mg intravenously). In the barostat protocol, a flaccid bag was introduced in the stomach and inflated at intra-abdominal pressure +2 mmHg, volume was recorded before and after administration of a liquid meal (300 kcal). Gastric emptying for solids and liquids was simultaneously assessed using the ¹⁴C-octanoic acid/¹³C-glycine breath test. During the drink test, volunteers drank at a rate of 15 mL/min until maximal satiation. Citalopram was compared with placebo using t-tests and mixed model analysis. RESULTS Citalopram induced a significant preprandial gastric relaxation (volume increase of 154 ± 55 mL vs. -38 ± 33 mL after placebo dosing; P < 0.05), whereas the postprandial volume increase was significantly decreased after citalopram treatment (F₁₂.₈₀ = 4.78, P < 0.0001; maximum volume increase was 304 ± 40 vs. 201 ± 54 mL after placebo and citalopram treatment respectively). Citalopram enhanced solid (123 ± 17 vs. 77 ± 6 min, P < 0.05) but not liquid emptying (62 ± 6 vs. 57 ± 4 min). Satiation scores during the drink test were lower after citalopram (F₁₉.₁₅₃ = 2.02, P = 0.01; volunteers drank 998 ± 129 vs. 765 ± 79 mL after citalopram and placebo treatment respectively). CONCLUSION The observed effects indicate a role for serotonin in the control of gastric motility and food intake.
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The effect of megestrol acetate on oral food and fluid intake in nursing home residents: a pilot study.
Simmons, SF, Walker, KA, Osterweil, D
Journal of the American Medical Directors Association. 2005;(3 Suppl):S5-11
Abstract
OBJECTIVES The objective of this study was to evaluate the effect of megestrol acetate (Megace OS; Bristol-Myers Squibb, Princeton, NJ) on the oral food and fluid intake of nursing home (NH) residents under two conditions: usual NH care and optimal mealtime feeding assistance. DESIGN AND SETTING We conducted a prospective, preliminary trial in four NHs. PARTICIPANTS Participants (n = 17) were recruited from a larger study designed to assess nutritional care quality. Eligibility for the Megace OS trial required participants to consistently eat less than 75% of most meals under both usual NH care and optimal feeding assistance conditions at baseline. INTERVENTION Megace OS, an oral liquid suspension of megestrol acetate, was given daily in a 400-mg dose for 63 days. MEASUREMENTS Each participant's oral food and fluid intake was monitored weekly for 1 day (three meals) during which research staff conducted direct observations of usual NH care (weeks 1, 3, and 5 and day 63) or provided optimal feeding assistance (weeks 2, 4, and 6). Average total percent intake was compared from baseline across the assessment weeks of the trial under the two mealtime care conditions. RESULTS Megace OS had a significant effect on oral food and fluid intake only under the optimal mealtime feeding assistance condition, in which average total percent eaten increased from 50% (+/-15%) at baseline to 63% (+/-14%) post-63 days of the trial. There was no change in participants' oral food and fluid intake under the usual NH care condition (average total percent intake at baseline 43% +/- 12% vs. 43% +/- 20% post-63 days). CONCLUSION The results of this preliminary study suggest that Megace OS is not an effective nutritional intervention to increase oral intake under usual NH care conditions, which is often characterized by inadequate feeding assistance. However, Megace OS in combination with optimal mealtime feeding assistance does significantly increase oral intake in a frail NH sample at high risk for weight loss.
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Cardiovascular responses to water drinking: does osmolality play a role?
Brown, CM, Barberini, L, Dulloo, AG, Montani, JP
American journal of physiology. Regulatory, integrative and comparative physiology. 2005;(6):R1687-92
Abstract
Water drinking activates the autonomic nervous system and induces acute hemodynamic changes. The actual stimulus for these effects is undetermined but might be related to either gastric distension or to osmotic factors. In the present study, we tested whether the cardiovascular responses to water drinking are related to water's relative hypoosmolality. Therefore, we compared the cardiovascular effects of a water drink (7.5 ml/kg body wt) with an identical volume of a physiological (0.9%) saline solution in nine healthy subjects (6 male, 3 female, aged 26 +/- 2 years), while continuously monitoring beat-to-beat blood pressure (finger plethysmography), cardiac intervals (electrocardiography), and cardiac output (thoracic impedance). Total peripheral resistance was calculated as mean blood pressure/cardiac output. Cardiac interval variability (high-frequency power) was assessed by spectral analysis as an index of cardiac vagal tone. Baroreceptor sensitivity was evaluated using the sequence technique. Drinking water, but not saline, decreased heart rate (P = 0.01) and increased total peripheral resistance (P < 0.01), high-frequency cardiac interval variability (P = 0.03), and baroreceptor sensitivity (P = 0.01). Neither water nor saline substantially increased blood pressure. These responses suggest that water drinking simultaneously increases sympathetic vasoconstrictor activity and cardiac vagal tone. That these effects were absent after drinking physiological saline indicate that the cardiovascular responses to water drinking are influenced by its hypoosmotic properties.
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Effects of hydration and hyperventilation on cortical complexity.
Müller, V, Birbaumer, N, Preissl, H, Braun, C, Mayer-Kress, G, Lang, F
Experimental brain research. 2003;(3):341-55
Abstract
The effects of hydration and hyperventilation on cortical complexity were investigated in a sample of 19 healthy volunteers in a double-blind placebo design using magnetoencephalographic recordings. The subjects were asked to abstain from the intake of liquids 18 h before the study. Spontaneous magnetoencephalograms (MEG) were recorded before and after drinking 750 ml water (WAT group: nine subjects) or saline solution (SAL group: ten subjects) with eyes closed and open and during hyperventilation (HV) with eyes open. The MEG data were analysed using both linear (spectral power) and non-linear (pointwise dimension and largest Lyapunov exponent) algorithms. The prediction that intake of water, because of induced cell swelling, will lead to an increased synchronization and a decreased complexity of the spontaneous MEG during hyperventilation was confirmed. Hyperventilation following the drinking condition produced an increase in all power spectra with a stronger increase of delta and theta power after drinking of water. This synchronization of spontaneous MEG is accompanied by a general significant decrease of cortical complexity, especially after water drinking. Moreover, cortical complexity was inversely related to delta and theta power and partly also to alpha power. The SAL and WAT groups showed different relations between alpha power and dimensional complexity during HV: whereas in the SAL group the correlations between these measures became more negative during HV, they reversed in the WAT group to become positive. The synchronizing effect of hyperventilation, leading to a decrease of cortical complexity, is related in the SAL group to delta, theta and alpha power, whereas in the WAT group only delta and theta activity contribute to a reduction of cortical complexity.